Interposer assemblies with molded plastic plates and inserted metal contacts in the plates are used for forming electrical connections between contact pads on opposed substrates. The contacts are spaced very close together in land grid array rows and columns to establish a large number of differential pair signal and ground connections extending through the plate.
Increased circuit speed requires transmission of differential signals through interposer plates at signal frequencies of 10 or more gigahertz. Transmission of high-frequency signals through conventional interposer plates with short, closely spaced single circuit path contacts and very fast rise times for the signals increases signal impedance and degrades signal strength. High-frequency signaling can cause cross-talk between adjacent pairs of signal circuit path contacts. FIGS. 10 and 11 illustrate a conventional interposer assembly with contacts forming single circuit paths between pads on opposed substrates.
The prior art interposer assembly shown in FIGS. 10 and 11 uses contacts 200 with single circuit paths 202 extending between contact points 204. The portions or stubs 206 of the contacts 200 extending from points 204 to free ends 208 do not carry current. These stubs extend outside of the electrical current path or loop for the contact and act as antennas. The antennas radiate energy and increase signal loss, particularly at high signal frequencies.